[1] HOKKAIDO UNIV,SCH MED,DEPT NEUROL,KITA KU,SAPPORO,HOKKAIDO 060,JAPAN
[2] HOKKAIDO UNIV,SCH MED,DEPT PATHOL 1,KITA KU,SAPPORO,HOKKAIDO 060,JAPAN
[3] HOKUYUKAI NEUROL HOSP,SAPPORO,HOKKAIDO 060,JAPAN
[4] YAMAGATA UNIV,SCH MED,DEPT INTERNAL MED 3,YAMAGATA 99023,JAPAN